[T3] Update with a Bowl Full of Rust Flakes

Jim Adney jadney at vwtype3.org
Sat Jul 23 18:57:23 PDT 2011

On 23 Jul 2011 at 21:28, SCS Crewcab wrote:

> Even with oil, fuel with ethanol will still attract moisture. Since oil 
> and gas is lighter than water, the water will end-up on the bottom of 
> the tank. If I was storing a car, I would drain the tank and remove the 
> fuel tap so any condensation that forms in the tank will drain out.

I'm sure situations can vary, but I've stored cars for years with no 
difficulty, and the summers here are far from arid. The key is to 
store them with a full tank and make sure there are no excess places 
for air to get in or out. There should be one and only one vent path.

Assuming you don't have liquid water getting into the tank, the main 
source of water getting in there is from dew forming in the air space 
above the gas. This happens because barometric pressure changes cause 
air to "breath" in and out of the tank. Minimize the amount of air 
space and you minimize the "breathing."

Gasoline must also have some corrosion preventative properties, 
because you never see rust in tanks that have been in regular 
service, unless water gets splashed in there for some reason. I 
suppose adding some oil to the gas might offer some additional 
protection, but I doubt if there's much to gain.

Ethanol may make some difference, but ethanol will keep a certain 
amount of water in solution without a problem. I'm not sure, but I 
suspect that once there's more water in there than the ethanol will 
hold, it is no longer hydroscopic.

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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